Field of the Invention
The present invention relates to a thermostatic valve and a cooling system for a motor vehicle engine.
Description of the Background Art
Thermostatic valves are known in the prior art and are used in a cooling system of a liquid-cooled internal combustion engine to control a coolant circuit with the goal of reaching the optimal temperature in the internal combustion engine as rapidly as possible, to maintain it under all operating conditions, and to prevent overheating in the engine. This is especially important for the operational life, fuel consumption, and exhaust gas production of the internal combustion engine. The thermostatic valve is generally used as a 3/2-way valve in the coolant circuit at a too low engine temperature after startup or at a too low load while the motor vehicle is being driven. Because of the thermostatic valve, the coolant flowing out of the engine flows not through a radiator of the coolant circuit, but directly via a bypass line back again to the engine.
EP 2019915 B1, which corresponds to U.S. Pat. No. 8,220,720, discloses a thermostatic valve for a cooling system of an internal combustion engine, which has a thermostatic operating element disposed in a mixing chamber. The thermostatic drive element acts as a drive element for a main valve element, to be disposed between the mixing chamber and a connection from a coolant radiator, and for two bypass valve elements, which are to be arranged upstream of the mixing chamber and are disposed relative to a valve seat such that upon an extension motion of the thermostatic operating element the initially closed bypass valve element opens and the other closes again due to a slide unit upon a further extension motion. In this case, a common bypass valve element is provided, which has a section acting as the bypass valve slide and a bypass valve disc connected upstream in the extension direction of the thermostatic operating element, a common valve seat being provided between them. Further, a pressure relief valve opening toward the mixing chamber is provided in the common valve seat.
EP 2021595, which corresponds to U.S. Pat. No. 8,091,517, also shows a thermostatic valve for a cooling system of an internal combustion engine with a thermostatic operating element, which is to be disposed in a valve chamber and which acts as a drive element for a main valve element, to be disposed between an engine outlet and a connector leading to a coolant radiator, and for a bypass valve element, which is to be disposed between the engine outlet and an engine inlet, is designed as a valve slide, and has a pressure relief function. It is provided in this case that in addition to the valve slide, the bypass valve element is provided with a valve disc which is assigned to the valve slide in the extension direction of the thermostatic operating element. Further, a component, which forms both a valve seat for the valve slide and a valve seat for the valve disc, is assigned to the valve slide and the valve disc.